Gotta echo what everyone else said. First customs are always choppy-you learn from experiencing. Even the big boys didn't pop out amazing pieces at first go. Plan it out, take it slow, take your time and don't judge yourself to hard. Customs can always be made again later or taken apart and redone.
Personally, with that type of body I'd do a little bit of both sculpting and real cloth. ML's are easier because of their unique body, and allot of people love them because of their articulation, but bodies like the one you posted have a TON of articulation. Honestly it looks like a 12'' body shrunk down. Sculpting it completely would look nice, but it would have to have allot of time put into it so the sculpting doesn't hinder any articulation or get rubbed off. Id say sculpt the little things, like boots, gloves, hair, yadda yadda and use real cloth for the clothes. You don't need to find any fancy fabric, just chop up and old tshirt and keep sizing it till you get what you like. If your making clothes for a 6 inch figure, a tshirt is gonna give you quite a bit of extra fabric to play trial and error with.
Pew Pew Pew.